1. Field of the Invention
The present invention relates to a display apparatus utilizing a light emitting device using an organic compound. More specifically, the present invention relates to a display apparatus using an organic electroluminescent (EL) device (OLED) which emits light by applying an electric field to a thin film made of an organic compound.
2. Description of the Related Art
In a color display as well as an organic EL display, it is an important element for displaying an image with fidelity that a color reproduction range is large. Generally, in a color display, color is reproduced using a combination of three sub-pixels of RGB that are three primary colors of light as one pixel, and each chromaticity of RGB determines a color reproduction range of the color display.
As a standard of measure of a color gamut representing a color reproduction range, for example, there is National Television System Committee (NTSC). According to the NTSC system, RNTSC (0.67, 0.33), GNTSC (0.21, 0.71), and BNTSC (0.14, 0.08) are adopted as a CIE chromaticity of the RGB three primary colors, and WNTSC (0.31, 0.316) is adopted as a CIE chromaticity of white color. As shown in FIG. 7, the area of a triangle surrounded by these three points is defined as a color gamut of 100% on CIE chromaticity coordinates.
As the conventional art of enlarging the color gamut of a display, U.S. Pat. No. 6,570,584, International Publication No. WO2004/036535, and U.S. Patent Application Publication No. 2006/0006797 propose introducing a plurality of sub-pixels having colors outside of the color gamut defined by RGB sub-pixels as well as the sub-pixels of three colors of RGB.
Certainly, the color gamut can be enlarged by the techniques of the above-mentioned patent documents. However, in a display, it is important to reduce power consumption, and particularly in a display mounted on portable electronic equipment and a portable television, low power consumption is demanded so as to keep the driving time by a battery long. In contrast, the techniques of the above-mentioned patent documents have a problem in that the decrease in power consumption is not considered.